/*
 *                               POK header
 *
 * The following file is a part of the POK project. Any modification should
 * be made according to the POK licence. You CANNOT use this file or a part
 * of a file for your own project.
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2021 POK team
 */

/* k_cosf.c -- float version of k_cos.c
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#ifdef POK_NEEDS_LIBMATH

#include "math_private.h"
#include <libm.h>

static const float one = 1.0000000000e+00, /* 0x3f800000 */
    C1 = 4.1666667908e-02,                 /* 0x3d2aaaab */
    C2 = -1.3888889225e-03,                /* 0xbab60b61 */
    C3 = 2.4801587642e-05,                 /* 0x37d00d01 */
    C4 = -2.7557314297e-07,                /* 0xb493f27c */
    C5 = 2.0875723372e-09,                 /* 0x310f74f6 */
    C6 = -1.1359647598e-11;                /* 0xad47d74e */

float __kernel_cosf(float x, float y) {
  float a, hz, z, r, qx;
  int32_t ix;
  GET_FLOAT_WORD(ix, x);
  ix &= 0x7fffffff;      /* ix = |x|'s high word*/
  if (ix < 0x32000000) { /* if x < 2**27 */
    if (((int)x) == 0)
      return one; /* generate inexact */
  }
  z = x * x;
  r = z * (C1 + z * (C2 + z * (C3 + z * (C4 + z * (C5 + z * C6)))));
  if (ix < 0x3e99999a) /* if |x| < 0.3 */
    return one - ((float)0.5 * z - (z * r - x * y));
  else {
    if (ix > 0x3f480000) { /* x > 0.78125 */
      qx = (float)0.28125;
    } else {
      SET_FLOAT_WORD(qx, ix - 0x01000000); /* x/4 */
    }
    hz = (float)0.5 * z - qx;
    a = one - qx;
    return a - (hz - (z * r - x * y));
  }
}

#endif
